One form of computer graphics is to develop a sequence of video image frames of an object scene from object scene information. The sources of object scene information include computer databases and computer programs. The object scene information includes visual characteristics of an object scene, such as color and movement. Typically, one or more programs comprising a renderer process object scene information.
More specifically, a video image frame includes a color value for each pixel of a monitor or display. Pixels are the smallest resolution element of the monitor or display. Processing object scene information corresponding to the general area of the pixel determines a color for a given pixel.
Computer graphics systems typically develop each video image frame of computer animated video by point sampling the general location of a given pixel in an object scene. Essentially, a renderer processes object scene information to calculate a color value of an object scene at an infinitesimal point within the object scene. The renderer then averages color values of a set of point samples in the general area of a pixel to compute a color for the pixel. The distribution or positioning of the point samples is either regular or non-regular. The renderer generally accomplishes a regular distribution with a rigid, evenly spaced grid of point samples. Off-setting each point sample in an otherwise evenly spaced grid by a pseudo-randomly determined amount is an example of a non-regular distribution of point samples.
Additionally, some computer graphics systems extend point sampling to simulate motion blur by distributing point samples within a period of time associated with a video image frame.
Furthermore, some computer graphics systems simulate depth of field by selecting, for a region of the image plane, a point through which to view an object scene on a simulated lens. The position of the point on the lens affects which objects in the object scene are projected onto the region of the image plane.
Other computer graphics systems reconstruct a view of an object scene by area averaging. Unlike the point sampling described above, area averaging calculates an actual view of an object scene in the general area of a pixel. The systems then compute a color value for the pixel from the view. The process is substantially more time consuming than point sampling, however, because these systems calculate a view of an entire area (instead of a set of points within the area).
Persons skilled in the art generally acknowledge that area averaging provides a more faithful reconstruction of a view of an object scene under certain circumstances than does point sampling. Point sampling, however, offers reduced computational complexity and allows for easy simulation of depth of field and motion blur. There is needed in the art, therefore, a means of reconstructing views of object scenes that provides the faithful image reconstruction of area averaging, but also provides reduced computational complexity and easy simulation of motion blur and depth of field.